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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

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anode is fixed. The rotation may be imparted by a water turbine or an
electric motor of adjustable speed. Much more perfect is the Fischer
stand made for his electrodes and suitable also for use with the Classen

dish (Fig. 22).

Another means for obtaining the rotation of the electrolyte is that pro-

FIG. 21.

FIG. 22.

posed by Frary and based on the principle that any conductor carrying
a current and situate in a magnetic field tends to move with a velocity
depending on the intensities of the current and of the magnetic field. The
arrangement of the apparatus is shown in Fig. 23. In practice, preference

is given to mechanical methods of agitation.
Practical Rules.—When use is made of
Winkler's electrodes,   which   are   the   most
practical, the electrolysis is carried out  in  a
beaker which is fairly tall and not too narrow.
3 -   The prescribed reagents are added, suitably
diluted so that the electrodes   remain com-
pletely immersed, and mixed.    The beaker is
placed on a stand of adjustable height or on
a tripod fitted with wire gauze if the elec-
trolysis is to be carried out in the hot.    The
electrodes are then arranged, care being taken
that the bottom of the cathode is about I
FIG. 23                  cm. from the bottom of the beaker and that

the anode is exactly in the middle of the gauze

cylinder and almost touches the base of the beaker. The latter is then
covered with a divided clock-glass with three semicircular gaps in each
half, so that three circular holes are left to take the stems of the

ting of two concentric gauze